Measuring the Immeasurable

By Bill Moore

Posted: 31 Aug 2010

I think we all need to stand up and give the folks at the United States EPA and Department of Transportation a round of applause for coming up with a way for American car buyers to better compare the economic and environmental merits of light duty motor vehicles. Below are two proposed approaches for displaying the energy efficiency and environmental impact of a full range new passenger cars and trucks from conventional vehicles to all-electric. The first proposed window sticker shows one of two options for an electric vehicle, the second is a similar option for a plug-in hybrid vehicle.

The reason the government is proposing these designs is to help car buyers better understand the consequences of a potential automobile purchase, be it an electric car, a plug-in hybrid, a conventional hybrid, or a non-hybrid. The numbers on these examples are, of course, purely suggestive approximations of what each vehicle might be expected to achieve. For example the $618 annual electricity cost would, naturally be based on local utility rates, how efficient the car is -- here measured as 34kWh per 100 miles, or 340 watt hours per mile -- and how many miles the owner drives in a year. Also, the charge time depends on what level of charging will be used: 110V or 208-240 V, and at what amperage. The higher the voltage and amperage (the rate at which current flows) the shorter the battery charging time.

Similarly, the environmental impact of the vehicle is based on vehicle emissions only, not on the upstream energy emissions of the power plant or oil refinery. Hence the electric car can have 0 greenhouse gas emissions and be rated 10 -- the best -- in terms of other air pollutants like NOx and SOx. Of course, the only way it can be a totally zero emission vehicle is for all of its electric power to come from a non-polluting, renewable energy source like wind, water, geothermal, or solar.

The second sticker option, the long vertical design contains similar information, but adds one key component not found in the first design: a large letter grade of A through D; A+ being the highest, D, the worst. I would think that while this design makes it very easy separating the good from the bad at a glance, I would imagine that carmakers would have serious issues with it. After all, who wants to slap a D sticker on their brand new 8-cylinder, 500 hp luxury four-door sport pickup costing $80,000? But then maybe that's the whole point. A vehicle with a D sticker will get in the range of 10 mpg in the city and 13 mpg on the highway, generating nearly 800 grams of CO2 per mile. You'll either embarrass carmakers into doing better, cause the less scrupulous to fudge their test numbers, or create a counter-culture of defiant consumer "under-achievers," automotively-speaking.

Interestingly, missing from these stickers are exaggerated fuel economy claims like those argued last year when GM proposed that the Volt would get 230 mpg. Certainly, under some circumstances that's possible; even my S10 burning E85 gets 84 mpg… going down hill with my foot off the accelerator.

Still, overall, I think this is a commendable effort, one that will, if consumers come to understand it and apply it, help move us nearer to a less petroleum-dependent transportation system.

Click here to view all of the proposed designs, which include not only stickers categorized by propulsion type but also by fuel, including ethanol and compressed natural gas.

EPA sticker for electric car

EPA sticker for plug-in hybrid car

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